Breastfeeding and Contaminants

Ed. Note: We provide articles from our publications from previous years for reference for our Leaders and members. Readers are cautioned to remember that research and medical information change over time.

Is breastfeeding hazardous to babies' health? This was the allegation earlier this year when the US press published stories about two environmental contaminants--heptachlor and dioxin--that were reported to be present at dangerous levels in breast milk. These reports shook the confidence of many nursing mothers, some of whom weaned their babies unnecessarily since these dangers later proved to be exaggerated.

Heptachlor and dioxin are man-made chemical compounds that are not biodegradable, that is, they cannot be broken down by natural processes. These compounds are fat soluble; when they are ingested by a living organism they settle in the fatty tissue and are not easily metabolized and excreted. When a mother's body mobilizes fat stores for energy to make milk, small amounts of these contaminants enter her milk.

In early March of this year it was discovered that cow's milk and other milk products contaminated with the pesticide heptachlor were being sold in eight of the United States: Arkansas, Kansas, Louisiana, Mississippi, Missouri, Oklahoma, Tennessee, and Texas.

Heptachlor, a suspected carcinogen, was banned in 1983 by the United States government for use on food crops. However, manufacturers were allowed to sell existing stores for crops not planned for consumption. According to the news reports, contaminated corn mash, a byproduct of the process used to make gasohol, was sold to dairy farmers as feed for their cattle. The cows ate the contaminated mash and the heptachlor was excreted into their milk at levels above legal limits.

Once the contamination was discovered, the tainted milk and other dairy products were removed from grocery store shelves. In addition, federal agencies quarantined and investigated the dairy farms in question. Pregnant and nursing mothers in the affected areas were cautioned to avoid milk and milk products until they were judged to be within the prescribed federal guidelines. As the investigation proceeded, however, uncertainty grew as to how long the dairy cattle had been fed the heptachlor-contaminated grain. Because the companies had kept such poor records it was impossible to confirm, but it seemed likely that contaminated feed had been distributed to dairy farms for more than a year.

Meanwhile emotions ran high, especially in Arkansas where ten percent of the dairies were affected and the Public Health Department would not clarify the extent of the health risks. The media highlighted possible dangers to the nursing baby before tests determined how much heptachlor was being excreted into breast milk and before safe levels had been defined. Early in the controversy a group of obstetricians at the University of Arkansas for Medical Sciences issued an advisory, warning all breastfeeding mothers to immediately stop nursing their babies, irrespective of whether or not they had drunk the contaminated milk. The press reports of safe levels of heptachlor in breast milk kept changing and at first there were no available facilities for testing breast milk. Eventually one private lab in Arkansas offered to test breast milk for heptachlor at no charge.

No doubt many nursing mothers weaned their babies during the scare. Hundreds more called their local LLL Leaders. La Leche League International also received many letters and phone calls. As one mother from northwest Arkansas wrote: "I enjoy nursing (four-month-old) Sean. I would like to continue, but not at the expense of his health."

La Leche League International contacted the Centers for Disease Control in Atlanta, Georgia, but because the problem fell within the responsibilities of the states, this federal agency could issue no public recommendations. Other government agencies, such as the Federal Drug Administration and the Environmental Protection Agency, claimed that because the levels of heptachlor reported were not a cause for concern they would make no statement. To determine the specific dangers to nursing mothers and babies, LLLI staff consulted members of the Professional Advisory Board and other knowledgeable scientists. These experts agreed that the levels of heptachlor that had been reported in breast milk were below the levels that were considered to be harmful. Spurred on by their recommendations, LLLI issued a press release stating that because of the undeniable benefits of breastfeeding and the lack of evidence to date, weaning was not advisable. Proper procedures were given for collecting breast milk for testing and guidelines were offered to help pinpoint mothers whose babies might be at higher risk.

The final resolution of the controversy came more than a month after the news of the contamination broke when the Centers for Disease Control issued a report containing the results of tests done on families who lived on the contaminated dairy farms. These families were at greatest risk because they had administered the contaminated feed, lived around it, and drunk the milk from the cows. None of the people who were most directly exposed showed any of the physical effects that large doses of heptachlor can produce, such as liver impairment. And the levels of heptachlor in their blood were only modestly higher than what would be expected from exposure to "background levels" of heptachlor, that is, levels that are present in the general environment. Only five percent of the farm families had levels higher than this. On the basis of these tests it was concluded that the general population was not at risk and no further testing of breast milk was needed. The report termed the risks to the nursing baby "negligible."

Just when the furor over heptachlor began to die down, dioxin contamination became the center of attention. The controversy began not with an accident or mishap but with a research paper presented at a meeting of the American Chemical Society on April 15. Dr. Arnold Schecter, a New York physician and researcher in the field of environmental contamination, asserted in his paper that a baby breastfed for one year would receive eighteen times the recommended lifetime dose of the toxic herbicide dioxin from his mother's milk. The press, in covering the event, overlooked the details of the presentation and focused on this one point, reporting the hypothesis as if it were an established fact, which it was not. Dr. Schecter's hypothesis was based on his analysis of fatty tissue samples taken from women during autopsies. He had not tested breast milk for dioxin, nor had he examined babies or children for evidence of dioxin toxicity. He had simply estimated possible levels of dioxin in breast milk based on the amount of dioxin he found in the tissue samples.

This time the response from national health organizations was immediate. Within the day the Centers for Disease Control issued a statement pointing out the errors and inconsistencies of the press reports and disputing Dr. Schecter's conclusions. The statement said that safe levels of dioxin had never been established for humans. It also pointed out that "substitutes for human milk are not entirely free of these compounds and may have higher metal levels" and added that "the amount of these chemicals present in human milk does not make a significant contribution to the overall lifetime exposure in humans."

LLLI was advised by a representative of the Centers for Disease Control that this statement was about to be released. LLLI staff members reviewed this information with the Professional Advisory Board and prepared a press release, again affirming the value of breast milk, advising against weaning, and offering suggestions for ways women can minimize their exposure to environmental contaminants. A short time later the American Academy of Pediatrics also issued a statement concurring with those made by LLLI and the Centers for Disease Control.

It is true that environmental contaminants are present everywhere and are also present, in low levels, in breast milk, Naturally every mother wants to ensure that her baby grows up in the safest and healthiest environment. The issue is complex, and oversimplified information in the popular press often creates a lot of worry for nursing mothers. Studies are continuing, but it seems certain that the known benefits of breast milk for babies far outweigh the risks of contamination. LLLI's Information Sheet, Environmental contaminants in Breast Milk, contains information on this issue that can be used in evaluating individual circumstances.

If and when such alarming reports appear in the press in the future, mothers can count on LLLI to investigate the situation, consult with authorities, and inform our members about any documented, confirmed dangers. Meanwhile, experts from the American Academy of Pediatrics, the US Centers for Disease Control, and LLLI's Professional Advisory Board agree that mothers can continue to enjoy breastfeeding their babies and know that its benefits have withstood the test of time.

Editor's note: Special thanks to Julie Stock, the LLLI staff person who served as contact person on these issues and who contributed significantly to this article.